Explanation:

Sahel, Arabic Sa?il, semiarid region of western and north-central Africa extending from Senegal eastward to The Sudan. It forms a transitional zone between the arid Sahara (desert) to the north and the belt of humid savannas to the south. The Sahel stretches from the Atlantic Ocean eastward through northern Senegal, southern Mauritania, the great bend of the Niger River in Mali, Burkina Faso (formerly Upper Volta), southern Niger, northeastern Nigeria, south-central Chad, and into The Sudan.

The semiarid steppes of the Sahel have natural pasture, with low-growing grass and tall, herbaceous perennials. Other forage for the region’s livestock (camel, pack ox, and grazing cattle and sheep) includes thorny shrubs and acacia and baobab trees. The terrain is chiefly of the savanna type, with little continuous cover and a dangerous tendency to merge into desert because of overstocking and overfarming. At least eight months of the year are dry, and rain, confined to a short season, averages 4–8 inches (100–200 mm), mostly in June, July, and August. There are also wide areas of pasturage watered by the flooding Niger and Sénégal rivers. Modest crops of millet and peanuts (groundnuts) can be raised in many areas.

In the second half of the 20th century, the Sahel was increasingly afflicted by soil erosion and desertification resulting from growing human populations that made more demands upon the land than previously. Town dwellers and farmers stripped the tree and scrub cover to obtain firewood and grow crops, after which excessive numbers of livestock devoured the remaining grass cover. Rainfall runoff and the wind then carried off the fertile topsoils, leaving arid and barren wastelands.